Editorial note: Figures on this page reflect the 2026 Medicare program year and are cross-referenced against the official Centers for Medicare & Medicaid Services (CMS) publications. Always confirm current numbers before making enrollment decisions.
The purpose of Medicare Supplement (Medigap)
Medicare Supplement (Medigap) is designed to supplement Original Medicare — not replace it. You must be enrolled in Part A and Part B to buy a Medicare Supplement (Medigap) policy. Medicare Supplement (Medigap) then helps pay for some of the remaining out-of-pocket costs Original Medicare leaves to you: Part A and Part B deductibles, the 20% Part B coinsurance, hospital coinsurance, and (on certain plans) limited foreign travel emergency care.
Key principles to understand
- Requirement: You must have Medicare Part A and Part B to buy a policy.
- Structure: Policies cover one individual; spouses must buy separate policies.
- Provider choice: You can see any doctor or specialist nationwide who accepts Medicare — no network.
- No referrals: Visit specialists without going through a primary care gatekeeper.
- Guaranteed renewability: Policies cannot be canceled due to health conditions as long as premiums are paid on time.
- No prescription drug coverage: Medicare Supplement (Medigap) does not include Part D. See below.
Standardized plan types
Medicare Supplement (Medigap) plans are standardized by the federal government and labeled by letters (A, B, C, D, F, G, K, L, M, N). Each lettered plan offers the same coverage no matter which insurance company sells it — a Plan G from one carrier covers the same claims as a Plan G from another. Premiums, customer service, and rate history can differ between carriers. Compare the standardized chart on the Medicare.gov "Compare Medicare Supplement (Medigap) plan benefits" page.
- Plan F & Plan C: Available only to those eligible for Medicare before January 1, 2020.
- Plan G: Commonly selected by people newly eligible for Medicare; covers the same benefits as Plan F except for the annual Part B deductible.
- Plan N: Lower premiums in exchange for small copays for some doctor and emergency-room visits.
- High-deductible Plans F & G: Lower monthly premium with a higher annual deductible before Medicare Supplement (Medigap) begins paying.
Open Enrollment Period & guaranteed-issue rights
Your 6-month Medicare Supplement (Medigap) Open Enrollment Period begins the first month you are 65 or older and enrolled in Medicare Part B. During this one-time window, insurance companies cannot use medical underwriting — they cannot deny you a Medicare Supplement (Medigap) policy, place conditions on it, or charge you more because of your health, as defined by Medicare.gov.
Guaranteed-issue rights (also called "Medicare Supplement (Medigap) protections") are separate, limited situations — for example, losing certain employer coverage or leaving a Medicare Advantage plan within a defined window — in which carriers must sell you specific Medicare Supplement (Medigap) policies without medical underwriting. Not every situation qualifies. Review the exact list on the Medicare.gov guaranteed-issue rights page.
What Medicare Supplement (Medigap) covers
- Part A hospital coinsurance and additional hospital days after Part A benefits are used.
- Part B coinsurance or copayments.
- Blood transfusion costs (first 3 pints).
- Part A hospice care coinsurance or copayments.
- Skilled nursing facility care coinsurance.
- Foreign travel emergency care up to plan limits (on certain plans).
What Medicare Supplement (Medigap) does not cover
Medicare Supplement (Medigap) does not cover prescription drugs. To get outpatient drug coverage — and to avoid the Part D late-enrollment penalty — you generally need to enroll in a separate Medicare Part D prescription drug plan when you are first eligible, unless you have other creditable drug coverage.
- Prescription drugs — a separate Part D plan is required.
- Long-term care (such as extended nursing home stays).
- Routine dental, vision, or hearing care.
- Eyeglasses and hearing aids.
- Private-duty nursing.
Medicare Supplement (Medigap) compared with Medicare Advantage
- See any provider that accepts Medicare nationwide.
- More predictable out-of-pocket costs after premiums.
- Generally higher combined monthly premiums.
- A separate Part D drug plan is required.
- Use the plan's network of providers.
- Some plans have a $0 monthly plan premium in addition to Part B.
- Drug coverage is usually included in the plan.
- Includes an annual in-network out-of-pocket maximum.
Common mistakes to avoid
- Waiting past the 6-month Medicare Supplement (Medigap) Open Enrollment Period, when carriers may use medical underwriting.
- Assuming Medicare Supplement (Medigap) includes prescription drugs — it does not; a separate Part D plan is needed to have drug coverage and to avoid the Part D late-enrollment penalty.
- Comparing plans by company name instead of plan letter — because benefits within a lettered plan are standardized.
- Overlooking household discounts, guaranteed-issue rights, or a carrier's rate-increase history when comparing quotes.
- What: Medicare Supplement (Medigap) is private supplemental insurance that pays after Original Medicare on covered services.
- Why it matters: Original Medicare has no annual out-of-pocket cap, and Medicare Supplement (Medigap) helps make those costs more predictable while allowing you to see any Medicare-accepting provider.
- How: Enroll during your 6-month Medicare Supplement (Medigap) Open Enrollment Period, add a separate Part D plan, and compare plan letters (not brand names) alongside carrier premiums and rate history.
Medicare has neither reviewed nor endorsed this information. For a complete list of plans in your area, call 1-800-MEDICARE (TTY: 1-877-486-2048).